lib/mlton/basic/fold.sig

   1 (* Copyright (C) 2009 Matthew Fluet.
   2  * Copyright (C) 1999-2006 Henry Cejtin, Matthew Fluet, Suresh
   3  *    Jagannathan, and Stephen Weeks.
   4  *
   5  * MLton is released under a BSD-style license.
   6  * See the file MLton-LICENSE for details.
   7  *)
   8
   9 signature FOLD_STRUCTS =
  10    sig
  11       type 'a t
  12       type 'a elt
  13
  14       val fold: 'a t * 'b * ('a elt * 'b -> 'b) -> 'b
  15    end
  16
  17 signature FOLD =
  18    sig
  19       include FOLD_STRUCTS
  20
  21       val foldi: 'a t * 'b * (int * 'a elt * 'b -> 'b) -> 'b
  22       val foreachi: 'a t * (int * 'a elt -> unit) -> unit
  23       val foreach: 'a t * ('a elt -> unit) -> unit
  24       (* keepAll (l, f) keeps all x in l such that f x. *)
  25       val keepAll: 'a t * ('a elt -> bool) -> 'a elt list
  26       (* keepAllMap (l, f) keeps all y in l such that f x = SOME y.*)
  27       val keepAllMap: 'a t * ('a elt -> 'b option) -> 'b list
  28       val last: 'a t -> 'a elt
  29       val layout: ('a elt -> Layout.t) -> 'a t -> Layout.t
  30       val length: 'a t -> int
  31       val map: 'a t * ('a elt -> 'b) -> 'b list
  32       val mapi: 'a t * (int * 'a elt -> 'b) -> 'b list
  33       (* removeAll (l, f) removes all x in l such that f x. *)
  34       val removeAll: 'a t * ('a elt -> bool) -> 'a elt list
  35       (* The "rev" versions of functions are there for efficiency, when it is
  36        * easier to fold over the input and accumulate the result in reverse.
  37        *)
  38       val revKeepAll: 'a t * ('a elt -> bool) -> 'a elt list
  39       val revKeepAllMap: 'a t * ('a elt -> 'b option) -> 'b list
  40       val revRemoveAll: 'a t * ('a elt -> bool) -> 'a elt list
  41    end